The internal design of a circuit breaker's interrupter defines its performance. Two characteristics used to measure a circuit breaker's performance include the peak current (Ip) and the energy integral (I2t). Designing a circuit breaker that minimizes these quantities is desirable to increase performance and lower the interruption time, which may increase the longevity of the circuit breaker among other benefits.
A first type of prior art circuit breaker includes one pair of contacts including a moveable contact attached to an arm that pivots about a fixed point and a fixed contact attached to a terminal of the circuit breaker. The contact pair remains pressed together until the circuit breaker trips, which causes the pair of contacts to physically separate, thereby breaking the flow of current therethrough. This first type of tripping mechanism is slow and not suitable for high-performance interruption.
A second type of prior art circuit breaker includes a rotating blade operating two pairs of contacts. A more complete description of the second type of prior art circuit breaker can be found in U.S. Pat. No. 4,910,485 to Mobleu et al. While the second type of prior art circuit breaker has a better interruption performance as compared to the first type with a single contact pair, a rotating blade operating two contact pairs is limited in its interruption performance. Specifically, to increase the interruption performance of such a circuit breaker, the rotating blade radius can be increased, which results in a sharp increase in the inertia of the moveable blade—as the inertia of the blade is proportional to the square of its radius. This sharp increase in inertia is disadvantageous as the necessary force to move the blade from a closed position to a tripped position is also sharply increased, which can result in a longer amount of time to interrupt the circuit.
Thus, a need exists for an improved apparatus. The present invention is directed to satisfying one or more of these needs and solving other problems.